The monsoon is a time that nature gives Kathmandu another chance.

The rising waters wash away the garbage piled up on the banks of the Bagmati and Bishnumati rivers. The unbearable stench of a river-turned-sewer temporarily disappears. And the rains seep down into the ground, recharging the valley's dangerously receding water table.

Because of the recent exodus from the countryside, Kathmandu Valley's population is now beyond its carrying capacity. This limit to growth is now evident in that most vital ingredient necessary for human life: water.

The water carried by the mains from the state-owned Nepal Water Supply Corporation (NWSC) is woefully inadequate in meeting urban demand. In the dry season its pumps only meet 40 percent of the total 200 million litres per day that the valley needs. It is a luxury to have pipes that actually carry water, and many residents have attached pumps to illegally extract water from the mains when water is flowing.

This is where traditional water spouts and centuries-old wells have proved their worth (See: 'Oh, well', #194). But because of the over-extraction of ground water, some of the wells are going dry. More ominously, it is now clear that Kathmandu Valley's groundwater is seriously contaminated with organic and chemical pollution.

The NWSC itself is now pumping out 30 million litres of water a day from Sainbu and Manahara to store in the two huge three million litre tanks just built with Japanese aid. The corporation also allows households as well as hotels, restaurants and industries to extract unlimited amounts of groundwater. Private tubewells and deep boring are now pumping out an estimated 10 million litres of ground water daily, a rate that many experts say is unsustainable because monsoon recharging of groundwater is insufficient to replenish it.

Seepage from septic tanks, leeching of chemicals dumped carelessly from garages, factories and workshops have now made much of even this water undrinkable. And the more the extraction takes place, the more the ground water is likely to be contaminated.

Studies of Kathmandu's groundwater by the Environment and Public Health Organisation (ENPHO) show it has high concentrations of nitrates, ammonia, iron and manganese. "Most of the household water supplies from underground water contains nitrate, but people don't know it can be harmful to their health," says environmental activist, Prakash Amatya.

The only solution so far is to purify the contaminated water, but most people are unable to afford the water testing and treatment. Iron removal costs a minimum of Rs 40,000, and it is another Rs 100,000 for removal of ammonia, depending on the amount of water and the scale of contamination. "Groundwater quality is alarming, and its getting worse," says ENPHO's Narayan P Upadhaya.

The government has two water analysis and treatment laboratories at NWSC and the Royal Nepal Academy of Science and Technology (RONAST), but these organisations have not been actively spearding awareness. There are also a handful of other labs run by the private sector. "Water analysis is important to show the quality of water we are using," says Surendra Parajuli, a technician at the Water Engineering and Training Centre, the oldest lab in the country. But in the past 15 years, only 2,000 people have had their water tested, and they were mostly hotels and factories, he adds. Getting testing done isn't the only problem. If nitrates are found, they are difficult to remove.

As groundwater extraction grows, water organisations in the Valley are trying to spread awareness among residents about economical use of water. Only 2 percent of the water supply is used for drinking and cooking. The remainder is mainly for cleaning and hygienic purposes. The problem lies with the rich and middle class households, where water is wasted on washing machines, toilet flushing, watering gardens and washing cars. A study by the Centre for Integrated Urban Development on household water use found that rich households with less than five members use more water than eight members of a poor family.

"There needs to be a change in the social attitudes in every household to help prevent the excessive use of water," says Amatya from the NGO Forum, who has just started 'value-based water use education' to raise awareness among Kathmandu Valley residents. Since April, Amatya and his team from the NGO Forum have been busy visiting neighbourhoods, both rich and poor, to talk about economic use of water. But it is an uphill battle to get people to not think only of themselves. Says Amatya: "It is sad, people know how important water is, yet they waste it."